MSDN Documentation

ADO.NET Best Practices

This document outlines recommended practices for using ADO.NET to build robust, performant, and maintainable data access solutions.

1. Resource Management (Connections and Commands)

Always ensure that database connections and commands are properly closed and disposed of to prevent resource leaks.

• Use the using statement for IDbConnection, IDbCommand, and IDataReader objects. This guarantees that their Dispose() method is called, even if exceptions occur.
• Avoid keeping connections open longer than necessary. Open a connection only when you need to execute a command and close it immediately afterward.

using (var connection = new SqlConnection("your_connection_string"))
{
    connection.Open();
    using (var command = new SqlCommand("SELECT * FROM Products", connection))
    {
        using (var reader = command.ExecuteReader())
        {
            while (reader.Read())
            {
                // Process data
            }
        }
    }
}

2. Parameterized Queries

Always use parameterized queries to protect your application against SQL injection attacks and to improve performance by allowing the database to cache query plans.

• Never concatenate user input directly into SQL statements.
• Use SqlParameter (or the appropriate provider-specific parameter class) to define parameters for your commands.

using (var connection = new SqlConnection("your_connection_string"))
{
    connection.Open();
    string productName = "Chai";
    string query = "SELECT ProductID, ProductName, UnitPrice FROM Products WHERE ProductName = @ProductName";
    using (var command = new SqlCommand(query, connection))
    {
        command.Parameters.AddWithValue("@ProductName", productName);
        using (var reader = command.ExecuteReader())
        {
            // ...
        }
    }
}

3. Efficient Data Retrieval

Retrieve only the data you need to minimize network traffic and memory consumption.

• Select only the columns required by your application. Avoid SELECT * in production code.
• Use SqlDataReader for forward-only, read-only access to data when you don't need to manipulate the data set.
• Use DataSet and DataTable when you need to work with disconnected data, perform client-side filtering, sorting, or have complex data relationships.

4. Error Handling

Implement robust error handling to gracefully manage database exceptions.

• Wrap data access code in try-catch blocks to handle SqlException (or provider-specific exceptions).
• Log errors effectively for debugging and monitoring.
• Provide meaningful feedback to the user without exposing sensitive database error details.

try
{
    // Data access code here
}
catch (SqlException ex)
{
    // Log the exception: ex.Message, ex.Number, etc.
    // Display a user-friendly error message
    Console.WriteLine("An error occurred while accessing the database.");
}

5. Connection Pooling

ADO.NET providers, such as SqlClient, implement connection pooling by default. This significantly improves performance by reusing database connections.

• Ensure your connection strings are consistent to take advantage of pooling.
• Do not disable connection pooling unless you have a specific, well-understood reason.

6. Asynchronous Operations

For applications that require high responsiveness, such as web applications and UIs, use asynchronous data access methods.

• Leverage methods like OpenAsync(), ExecuteReaderAsync(), ExecuteNonQueryAsync(), etc.
• This prevents the application's main thread from blocking while waiting for database operations to complete.

public async Task LoadDataAsync(string connectionString)
{
    using (var connection = new SqlConnection(connectionString))
    {
        await connection.OpenAsync();
        // ... execute commands asynchronously
    }
}

7. Transaction Management

Use transactions to ensure data consistency when performing multiple related database operations.

• Start a transaction using connection.BeginTransaction().
• Commit the transaction using transaction.Commit() upon successful completion.
• Rollback the transaction using transaction.Rollback() if any part of the operation fails.

using (var connection = new SqlConnection("your_connection_string"))
{
    connection.Open();
    var transaction = connection.BeginTransaction();
    try
    {
        // Command 1
        // Command 2
        transaction.Commit();
    }
    catch (Exception)
    {
        transaction.Rollback();
        throw; // Re-throw the exception
    }
}

8. Choose the Right Data Access Strategy

Select the ADO.NET component that best suits your needs.

• SqlDataReader: For simple, forward-only data reading.
• DataSet / DataTable: For disconnected data scenarios, complex data manipulation, and caching.
• DataAdapter: Bridges DataSet and the database, enabling efficient data loading and updating.